A flexible manufacturing system (FMS) comprises a pallet changer and a machining center. The pallet changer has a workstation and a robot for transferring pallets.
In the workstation, a plurality of pallets each having a workpiece are arranged in an endless type transfer means. By operating the transfer means, the robot sequentially faces the pallets. In addition, the robot has a holder for detachably holding the pallet. The robot is fixed in a predetermined position.
As an example, a pallet facing a holder is held by the holder and then a workpiece and the pallet thereof are moved from the workstation to a table of the machining center. Also, after machining the workpiece, the workpiece and the pallet on the table of the machining center are moved back to the initial position in the workstation.
After that, when machining a workpiece next to the machined workpiece, a transfer means is operated in such a manner that the workpiece faces the robot. Similarly, the workpiece and the pallet for the workpiece are transferred to machine the workpiece.
In addition, when machining a workpiece remote from the previously machined workpiece, the transfer means is moved along a long distance and then the workpiece that is currently being machined faces the robot. Thus, the workpiece and the pallet for the workpiece are transferred by the robot to machine the workpiece.
Such a transfer means has a tendency to become large, because the number of workpieces to be set in the transfer means increases so as to automatically operate the workstation for a long time. Accordingly, when exchanging the workpiece and the pallet for the workpiece, a selected workpiece is moved to the robot by operating the large transfer means. Consequently the transfer time is long and the workpiece exchanging efficiency is low.